FAST-02 Trial Shows Proton FLASH Radiotherapy Delivers 75% Complete Pain Relief for Thoracic Bone Metastases with No Serious Adverse Events
核心洞察
The FAST-02 clinical trial demonstrated that proton FLASH therapy achieved complete pain relief in 75% of evaluable patients with painful thoracic bone metastases (搜索) at three months.
The trial enrolled 10 adult cancer patients, treating metastases in ribs, clavicle, scapula, and sternum with a single 8 Gy fraction at ultra-high dose rates exceeding 40 Gy/second.
No serious treatment-related adverse events were observed, and no cardiac or pulmonary toxicities occurred despite treatment near the lungs, heart, and spinal cord.
Varian (搜索), the cancer-care business of Siemens Healthineers (搜索), has published results from the FAST-02 clinical trial, demonstrating that proton FLASH radiotherapy effectively reduces pain in patients with thoracic bone metastases (搜索) while maintaining a favorable safety profile. The findings, published in Radiotherapy and Oncology, represent the first clinical evaluation of FLASH therapy for bone metastases in the chest and only the second in-human proton FLASH trial conducted worldwide.
The trial enrolled 10 adult participants with various cancer types that had spread to bones, causing pain at disease sites in the ribs, clavicle, sternum, and scapula. Each participant received a single 8 Gy fraction delivered at an ultra-high dose rate greater than 40 Gy/second — more than 100 times faster than conventional radiation therapy.
Pain Relief Outcomes
Efficacy was assessed using participants' reported pain relief scores at one and three months post-treatment. Of the eight participants with three-month pain scores, six (75%) reported complete pain relief, and two (25%) experienced a partial reduction in pain. Among those with one-month pain scores, one reported stabilized pain while the other reported a partial pain response. Notably, no patients experienced cancer spread or recurrence at the FLASH-treated site during the follow-up period.
Safety in Proximity to Critical Organs
"The significance of FAST-02 lies in our treatment sites being bone metastases (搜索) within the thorax, meaning proximity to the lungs, heart and spinal cord," said Emily Daugherty, MD, associate professor of radiation oncology at the University of Cincinnati Cancer Center (搜索) and lead co-investigator of the trial. "Assessing critical organ side effects is essential for any future implementation of FLASH in deep-seated tumors."
No serious treatment-related adverse events were observed. Despite participants being treated for thoracic metastases, no cardiac or pulmonary toxicities were identified. The most common side effect was mild skin changes that resolved over time, and no moderate or severe radiation-related complications were found during follow-up.
Building on FAST-01
FAST-02 extends the findings of the earlier FAST-01 trial, which established the feasibility and safety of proton FLASH therapy in patients with extremity bone metastases (搜索). By advancing to thoracic sites adjacent to vital organs, FAST-02 provides critical safety data for future applications in deep-seated tumors.
Principal Investigator John Perentesis, MD, professor and director of the Cancer and Blood Disease Institute at Cincinnati Children's Hospital (搜索), led the trial alongside Dr. Daugherty. The study was conducted at the Cincinnati Children's/University of Cincinnati Proton Therapy Center in collaboration with Varian (搜索) Medical Systems and UC Health.
Technical Platform and Future Directions
For the FAST-02 trial, Varian (搜索)'s ProBeam proton therapy system was modified to enable ultra-high-dose-rate delivery for FLASH treatments, and the Eclipse treatment planning system was enhanced to support FLASH therapy planning. Varian is advancing its proton FLASH capabilities through an integrated approach encompassing planning, quality assurance, and radiation-delivery technologies.
"The next step for FLASH researchers is to perform larger, multi-center clinical trials across a range of cancer types," said Ricky Sharma, MD, PhD, head of clinical strategy at Varian (搜索). "We hope these trials will show how transformative this new treatment could be in the clinic."
FLASH therapy delivers treatment at ultra-high dose rates, typically in less than one second, and has demonstrated potential in preclinical studies to reduce damage to surrounding healthy tissues while maintaining effective tumor control. Analysis of the FAST-02 trial results will inform future clinical studies and further evaluation of FLASH technology.